1. Field of the Invention
The present invention relates to a micro-nano hierarchical structure for drag reduction and microbial adhesion prevention, which is fabricated to comprise metallic nano-structures present on metallic micro-structures in order to achieve drag reduction and anti-biofouling effects in an environmentally friendly manner, unlike toxic coatings and paints.
2. Description of Related Art
Ships and marine structures are always in contact with many marine organisms. Adhesion of marine organisms is a phenomenon in which unwanted organisms adhere to and grow on the surface of artificial structures submerged in sea water. Marine organisms include microorganisms, plants and animals. When marine organisms adhere to a ship, the roughness of the surface of the ship increases, and thus the frictional resistance of the ship increases, leading to a reduction in the ship speed. To recover this reduction in the ship speed, an increase in fuel consumption is required, leading to an increase in the emission of greenhouse gases. It has been reported that the adhesion of marine organisms causes an increase in fuel consumption of up to 40%. In addition, when the degree of adhesion of calcareous marine organisms was severe, the frictional resistance was estimated to increase to 80%.
In an attempt to prevent the adhesion of marine organisms, a method of coating the submerged portion of a ship with an antifouling paint was proposed. Conventional antifouling paints containing tin compounds have excellent antifouling performance, but since 2003 the use thereof has been restricted by the International Marine Organization (IMO) due to environmental pollution problems such as toxicity to marine organisms.
For this reason, environmentally friendly antifouling paints containing no tin compounds, and low-friction-type antifouling paints allowing marine organisms to be detached using the lubricity of silicone resin upon contact with seawater, are currently used to prevent contamination from being caused by the adhesion of marine organisms, etc. However, antifouling paints containing no tin compound have problems in that they also cause environmental pollution and have poor antifouling performance.
In addition, as environmentally friendly antifouling technology, a method of making a polymer-based functional surface to realize drag reduction and anti-biofouling effects was proposed. However, polymer materials have problems in terms of practical use, because they have poor durability.